1. Field of the Invention
The present invention relates to an in-vivo information acquisition system equipped with an in-vivo information acquisition apparatus introduced into inner part of a subject and an external control apparatus which generates a control signal for controlling activation/stoppage of the in-vivo information acquisition apparatus as well as to a drive method for the in-vivo information acquisition system, and more particularly, to the in-vivo information acquisition system equipped with the in-vivo information acquisition apparatus containing a battery and to the drive method for the in-vivo information acquisition system.
2. Description of the Related Art
As an in-vivo information acquisition apparatus which acquires information in the body of a subject, a capsule endoscope which acquires a state in the body as images for observation has been put into practical use. Being swallowed through the mouth of the subject and thereby introduced into the body, the capsule endoscope has a capability to pick up images one after another by moving in body cavities, for example, organs such as the stomach and the small intestine via peristalsis until discharged naturally.
Images picked up in the body by the capsule endoscope moving in the body cavities are sent to the outside one after another through wireless communications and accumulated in a memory provided in an external receiver. By carrying a receiver, the patient can act freely after swallowing a capsule endoscope until the capsule endoscope is discharged.
The capsule endoscope draws drive power from a battery contained in a casing, but it is not possible to dispose a switch or the like on an outer surface of the casing in order for an operator to activate/stop the capsule endoscope because internal circuits and the like are enclosed in the casing.
To deal with this, Japanese Patent Application Laid-Open Publication No. 01-224553 proposes a capsule endoscope system in which a reed switch operated by an external direct-current magnetic field is installed in a casing and a permanent magnet is installed in a storage case used to house and store a capsule endoscope. The reed switch includes two ferromagnetic reeds encapsulated in a glass tube, facing each other with a gap on one side. When a magnetic field equal to or larger than a predetermined threshold is applied externally, a north pole and a south pole are induced in respective reeds, bringing the two reeds into contact by magnetic attraction and thereby causing the reed switch to short-circuit. When the magnetic field falls below the predetermined threshold, the reed switch opens due to elasticity of the reeds.
The capsule endoscope described above is not driven before use when housed in the storage case in which the permanent magnet is disposed, and starts to be driven by being freed from the influence of the permanent magnet when taken out of the storage case. Consequently, the capsule endoscope can prevent battery drain which will occur if the capsule endoscope starts to be driven before starting to be used.